In the magnet wire industry, it is common practice to wind wire upon large spools having tapered end flanges. One type of spool used for holding large heavy quantities of wire is of a sheet metal construction similar to those disclosed in U.S. Pat. Nos. 3,176,932 and 4,140,289. It is also known to employ large spools of a molded plastic construction similar to that disclosed in U.S. Pat. No. 4,253,569. Wire is commonly dispensed from such spools to a winding device or other wire using equipment in a continuous operation which requires the attachment of wire in one spool to that in another spool. For this purpose, the wire is wound upon the spool in such a manner that a starting length of wire on the spool becomes accessible before the wire on the spool is entirely exhausted. This is usually accomplished by bringing the starting length out along the inside of an end flange from the spool barrel to an external point adjacent the outer periphery of the end flange. However, successive windings of wire wound upon the spool build up against the starting length at an angle. If the wire is of a soft material such as aluminum, the wire may be damaged at the crossover points. Abrasion and indentation of the starting length and end turns of the wire may be sufficiently severe as to make the wire unsuitable for further processing.
For spools with straight end flanges, it was heretofore known to protect the starting length of wire from damage by successive windings by providing a groove on the inner face of the end flange to receive the starting length. In U.S. Pat. No. 3,368,765, it is proposed to employ a wire-receiving groove in one end flange which extends along a chord of the end flange tangential to the spool barrel. Other examples of spools or reels having a groove formed in the inner face of a straight end flange are shown in U.S. Pat. Nos. 629,115, 1,625,503 and 3,398,357.
It is also known to employ a wire receiving groove on the inner face of a tapered end flange of a large spool of the types previously mentioned. In this known spool design, the groove is disposed on the inner face of the end flange along a line of intersection formed by an imaginary cutting plane parallel to the spool axis and extending through a chord of the end flange tangential to the spool barrel. A wire start end hole is formed in the end flange at the end of the groove near the outer periphery of the end flange for anchoring the free end of the starting length of wire to the spool. One disadvantage of this known construction is that the starting length of wire is not always properly retained in the protecting groove, especially when wire is being wound onto the spool at high velocities on the order of 7,000 feet per minute. Under the effect of centrifugal force, the starting length of wire may be forced from the groove and forms a loop, part of which may extend over the inner face of the end flange to be damaged by successive windings of wire. It has also been observed that the starting length of wire may become dislodged from the protecting groove when an inadvertent release in wire tension during winding of the first turns of wire results in one or more turns of wire becoming loose.